Plastic bottles, beverage PET bottles in particular, represent problematic waste. They pose a problem from the point of view of storage and disposal after use as well as from the point of view of possible separation and recycling. If these bottles are stored and put into waste after use without pressing, their large volume causes problems in storage, decreases economy of waste collection as well as economical efficiency of eventual disposal or recycling.
Because of aforementioned reasons, the patent documentation describes the effort to create easily collapsible or foldable plastic bottle made of PET or similar plastics; however, none of these solutions has been successful enough so that such collapsible bottles could be created for common market.
So far, the existing attempts to create collapsible bottles led only to creation of a possibility to fold the bottle after use; however, these bottles cannot be used for carbonated beverages.
For instance, WO 00/44630 describes a no-return bottle with gradually collapsing design of the side walls without a possibility of return to the original shape, the side walls having an accordion-like construction with a system of neighbouring folds. Each of these folds is created of two opposite surfaces of different width, and at least the smaller of the two surfaces is in the shape of arc. If such shape would be considered in relation to character of such created bellows ridges rather than to the folds, the condition of different width of the surfaces means that one half of each bellows ridge is of higher height or convexity than the second half. From this, the possibility of folding the bottle by light pressure is inferred. In practice, however, such bottle is even easily liable to spontaneous deformation, when the bottle shape deformation takes place particularly in the width direction due to the beverage weight, manipulation and storage; and also, such bottle is not suitable at all for carbonated beverages because it does not withstand the pressure acting from the interior on the bottle walls.
Another collapsible bottle has been described for instance in the EP 0 850 842 A 1 wherein a collapsible bottle is composed of accordion-like bellows ridges, whose upper walls or lower walls are provided with at least one circumferential groove. In these bottles, the groove creates reinforcement to increase their resistance against unwanted deformation and facilitates intentional folding of the bottle. In this case, however, the all-circumferential stamped stiffening, which is here to create a groove, results in impairment of dimensional symmetry between the upper and lower halves of the accordion-like bellows ridges of the bottle, which finally results in unwanted spontaneous deformations of bottles and impossibility of their filling with carbonated beverages.
Both aforementioned documents quote as the known state of the art the possibility to create accordion-like bottle with symmetrical bellows ridges, where the upper half of the bellows ridges is of the same shape and dimensions as the lower one, however, even this solution is useless in practice because of deformations.